Abstract
Gour, the first Sasanian capital, was founded by Ardeshir-e Bābakān, the founder of Sasanian empire. The extensive archaeological and historical studies have been done on this city so far, which has led to the identification of valuable archaeological evidence. One of the most important archeological evidence obtained during the excavations of this historical city is a tomb with Oval-shaped burials, that was identified in the western part of citadel. The discovery of this tomb in this part of the city near the fire temple surprised the researchers. The purpose of this study is to analyze the identity of the tombs. Gathering the data has been done by documentation and field studies, and the research method is descriptive-analytical. According to the studies and beliefs of scholars and archaeologists, the vicinity of the burial, which contains impure remains of the corpses (nasu), is not compatible with the fire temple where the sacred fire was kept and on the other hand is not in line with the common teachings of Zoroastrianism. The main questions of the research are: Is the construction of the tomb a new burial model in Sasanian period or is it an adaptation of an older model? Were the tombs or coffins of the tomb used to hold the bodies? Or were the ossuaries, where the bones were kept, after the performance of the Zoroastrian tradition “exposure”? Study of the historical and religious texts about the Sasanians and their predecessors and related archaeological finds suggests that the proximity of tombs as the site of unclean elements to the fire temple as a center for the preservation of the sacred fire is a new burial pattern, probably in early Sasanian period in Gour, based on the ancient Achaemenid tradition. This burial pattern continued in the middle of the Sasanian period in another way in the form of a ossuaries next to some fire temples.
Keywords: Achaemenids, Sasanian, Tomb, Ossuary, Fire Temple, Burial Pattern.

Introduction
Ardeshir was thinking of devising a new plan for the political, social and religious structure of the country, in consequence of the defeat of the last Parthian king and the construction of the city of Ardeshir Khowreh. By planning Irānshahr, he intended to implement Avestan norms such as class structures and the concentration of power and formalization of the Zoroastrian religion, which led to religious changes, in the territory of Iran.
Apart from the historical knowledge, the archeological excavations in the city of Ardeshir Khowreh, led to the recognition of new aspects of Sasanian culture and civilization that are sometimes compatible with historical narratives and sometimes cause ambiguities. Understanding the architecture of government and religious buildings is one of the important aspects of this knowledge. The formalization of the Zoroastrian religion at the beginning of the Sasanians, which was one of the clear messages of Ardashir, is materialized by the construction of large fire temples in the citadel of Ardeshir Khowreh. Praying and honoring the sacred fire in the fire temple is one of the prominent manifestations of the Zoroastrian religion, which was performed to sanctify the four elements of water, wind, earth, and fire.
What surprised the scholars during the excavation in the western part of the citadel, and it has been seen as contrary to the teachings of the Zoroastrianism, was the discovery of a tomb near the fire temple of Ardeshir Khowreh. According to Zoroastrian beliefs and Avestan texts, the human body after death due to the penetration of the devil (demon) in it is unclean and cannot be buried and the body should be exposed to the air or the “exposure“ and their bones finally in Ossuaries (daxmag) should be located at high altitudes.
The location of this tomb in the center of Ardeshir Khowreh and more strangely, near the fire temple and the sacred fire, and the proximity of clean and unclean elements, was a challenging archaeological question that surprised everyone, and no one had a clear answer. Now, in this research, the author is going to try to give a proper answer to the question of what and why this tomb was built in the middle of Ardeshir Khowreh and its vicinity by re-reading religious texts and opinions of old historians and new scholars and the opinion of the excavators of this tomb about Iranian religious thoughts and death. Let us find the fire temple and make hypotheses with a historical-analytical and archaeological approach to a comparative re-reading of the relationship between the Zoroastrianism and this burial pattern in the Sasanian period and before them.

Conclusion
The issue of death, beliefs of the world after death, and burial traditions in the Sasanian period is one of the most controversial issues that requires further reflection on historical sources and archaeological evidence even in pre-Sasanian times. The results of archaeological excavations in recent years, clarify some ossuaries and burials near and sometimes in a place connected to the fire temple, have been reported from some other fire temples, which to some extent pave the way for further research.
From the extinction of the Achaemenids to the beginning of the Sasanians, the Zoroastrianism survived without the help of central and official organizations. Because the Zoroastrianism was preserved and transmitted by local imperial dynasties and different clerical groups, a variety of beliefs were undoubtedly common in its thoughts. Although historical sources indicate that the Zoroastrian religion was chosen as the official religion during the Sasanian period and from the time of Ardashir I, but in fact the Zoroastrian religion was never uniform in the Sasanian period and this issue is evident in the rituals and burial ceremonies. Accordingly, with study the archaeological evidence and Pahlavi sources, it was determined that Ardashir I, after gaining power, sought to restore governmental and religious relations to the old tradition and rule of the first, the Achaemenid (pre-Parthian) dynasty. The tomb of Ardeshir Khowreh and its burial pattern was a new model of the ancient tradition that was adapted from the tomb of Darius I in a new way in the time of Ardashir I.
The ceremonial placement of corpses in oval-shaped coffins with lids in a painted room near the fire temple of Ardeshir Khowreh was the same tradition that Darius the Achaemenid had observed in his rock tomb, although Darius’s tomb was located in the heart of the rocks near the Ka’ba-ye Zartosht. The fire temple was built, but the tomb of Ardeshir Khowreh in the heart of the city was built on the ground, but with the same look and tradition, next to the huge fire temple. Therefore, it can be said that this burial tradition in the early Sasanian period was a new pattern of the ancient tradition, which is probably due to a deliberate return by Ardashir I to the old Iranian traditions or the older Zoroastrian religion in the time of Darius.
It should be noted that the Parthian catacomb tradition can also have been influential in the construction of the tomb of Ardeshir Khowreh. This burial pattern appears in tombs near fire temples in the early Sasanian period, such as the city of Ardeshir Khowreh and a similar example in Firouz Abad fire temple, was abolished with the rise of Kartir as a fanatical priest. However, according to the identification of Bandiyan and Palangerd fire temples, it can be said that from the middle of the Sasanian period, with the decline of the fanatical priest, this burial tradition continued with new pattern. For example, placing the ossuary instead of placing the body in the coffin. The tradition of burying the dead next to fire temples continues in the cultural life of Iran, an example of which is the burial that is performed today next to the fire temple of Firouz Abad. Also, burial next to shrines, which according to many scholars, many of them have been erected on the foundation of ancient fire temples in terms of location and archaeological evidence, is a continuation of this tradition of the Sasanian period.